Transportation-related industry employment does not include transportation occupations in non-transportation industries, such as truck drivers working for wholesale and retail stores. When employment in transportation occupations in non-transportation industries is included, total transportation-related employment would account for about 12 percent of U.S. civilian jobs.

SOURCE: U.S. Department of Labor, Bureau of Labor Statistics, Employment Status
of Civilian Population by sex and age ("A" Tables) and Employees on nonfarm
payrolls by industry ("B" Tables), available
at: http://www.bls.gov/cpsatabs.htm.